Whiplash

Choose one moving creature you can see within range. Both you and the opposing creature's sizes determine how this spell will affect them:

Smaller Creatures. If the opposing creature is one size smaller than you, once you take this reaction, this creature stops moving and must make a Dexterity saving throw with disadvantage or be knocked prone. If the opposing creature is two sizes smaller than you, once you take this reaction, this creature stops moving and automatically fails the spell's Dexterity saving throw and is knocked prone. They are also knocked 5 feet in the opposite direction that they had been moving. Any creature smaller than you by more than two sizes isn't affected by any additional effects.

Same-Sized Creatures. If the opposing creature is the same size as you, once you take this reaction, this creature stops moving, and must succeed a Dexterity saving throw or be knocked prone.

Larger Creatures. If the opposing creature is one size larger than you, once you take this reaction, this creature stops moving and must make a Dexterity saving throw with advantage or be knocked prone. If the opposing creature is two sizes larger than you, once you take this reaction, this creature loses 5 feet of movement, but is otherwise unaffected. Any creature larger than you by more than two sizes isn't affected by any additional effects.

Airborne Creatures. If the opposing creature is airborne, they fall 5 feet backwards in the opposite direction that they had been moving, and they are automatically knocked prone, regardless of their size. They can still move on their turn.